Field of the Invention
The present invention relates to a magnetic recording and reproducing apparatus of a type wherein magnetic recording and reproducing are conducted by a magnetic head disposed on the surface of a magnetic disk of a rigid substrate while the disk is rotated at a high speed. Particularly, it relates to such apparatus wherein a magnetic recording layer on the magnetic disk constitutes an oxide layer, a nitride layer or an oxidized coating film at at least its surface layer, and recording and reproducing are conducted by a magnetic head which is caused to substantially contact with the surface of the magnetic disk at at least the innermost cylinder, whereby the durability of the magnetic disk and the magnetic head can be improved, the spacing loss can be reduced, and high density recording is made possible.
As is well known, in a magnetic recording and reproducing apparatus of this type, a hard magnetic disk comprising a rigid substrate made of aluminum and a thin magnetic layer formed thereon by a method such as a fine magnetic powder coating method, a plating method or a sputtering method, is rotated at a high speed so as to produce a dynamic pressure between the magnetic disk and a flying magnetic head so that the magnetic head is lifted and floats with a certain flying height by a fine air bearing, while the magnetic recording and reading are conducted.
In order to accomplish high density magnetic recording with a magnetic recording and reproducing apparatus of this type, it is necessary to minimize the flying height of the magnetic head and to reduce the spacing loss. However, when the flying height is reduced to thereby reduce the spacing loss, there is the risk of collision between the magnetic head and the surface of the magnetic disk by the influence of the surface properties of the disk, vibrations at the high speed operations and so on, whereby a damage of the magnetic disk or a head crash may occur. This causes reduction in the durability. In order to eliminate this disadvantage, the flying height q for the magnetic head 2 has been determined to be in a range of 0.1 .mu.m-0.3 .mu.m so as to obtain the durability. Therefore, there has been limit in reducing the spacing loss and high density magnetic recording.
A conventional technique to obtain high density magnetic recording by reducing a flying height of the magnetic head is disclosed in, for instance, Japanese Unexamined Patent Publication No. 287002/1986. In the known technique, recording and reproducing are conducted by bringing the magnetic head into substantial contact with a magnetic disk with a vertical magnetic recording layer comprising a cobalt serise alloy film formed on a rigid substrate while the head and the disk are relatively moved at a high speed.
However, since the conventional technique adapted to perform recording and reproducing by bringing the magnetic head substantially into contact with the surface of the vertical magnetic recording layer constituted by a metallic film or an alloy film having a low hardness, a problem such as a damage to the magnetic disk or a head crash may easily occur and the durability tends to be low.
The present invention is to eliminate the above-mentioned problem and is to provide a magnetic recording and reproducing apparatus of a type wherein a magnetic disk having a magnetic recording layer formed on a rigid substrate is rotated at a high speed, and magnetic recording and reproduction are conducted by a magnetic head disposed on a surface cf the disk, the magnetic recording and reproducing apparatus being characterized in that the magnetic recording layer constitutes an oxide layer, a nitride layer or an oxidized coating film at at least its surface layer, the magnetic recording and reproducing are conducted by the magnetic head which is caused to be substantially in contact with the surface of magnetic disk at at least an innermost cylinder of the magnetic disk.